The present invention is related to gas treatment of products, specifically food and similar products, using gas jets which impinge upon the products for e.g. cooling, heating or drying them.
Devices for cooling or heating food products are known from e.g. U.S. Pat. No. 4,679,542 to Donald P. Smith et al. These devices comprise a high-pressure gas plenum which communicates with upper and lower ducts defining a treatment area therebetween and having a plurality of nozzles for ejecting gas jets vertically into the treatment area. The food products to be treated are supported by a conveyor belt that transports them through the treatment area.
However, the control of the flow of gas in the prior art devices presents specific problems. Further, the design of those devices is quite complex, resulting in difficulties in meeting the high hygienic requirements of the food industry. Also, the maintenance of the prior art devices is time-consuming, and the intervals between successive shutdowns are short.